Indeed, Mr. Sperber, a member of the Jean-Nicod research institute in Paris, first developed a version of the theory in 2000 to explain why evolution did not make the manifold flaws in reasoning go the way of the prehensile tail and the four-legged stride. Looking at a large body of psychological research, Mr. Sperber wanted to figure out why people persisted in picking out evidence that supported their views and ignored the rest — what is known as confirmation bias — leading them to hold on to a belief doggedly in the face of overwhelming contrary evidence.

Other scholars have previously argued that reasoning and irrationality are both products of evolution. But they usually assume that the purpose of reasoning is to help an individual arrive at the truth, and that irrationality is a kink in that process, a sort of mental myopia. Gary F. Marcus, for example, a psychology professor at New York University and the author of “Kluge: The Haphazard Construction of the Human Mind,” says distortions in reasoning are unintended side effects of blind
evolution. They are a result of the way that the brain, a Rube Goldberg mental contraption, processes memory. People are more likely to remember items they are familiar with, like their own beliefs, rather than those of others.

What is revolutionary about argumentative theory is that it presumes that since reason has a different purpose — to win over an opposing group — flawed reasoning is an adaptation in itself, useful for bolstering debating skills.

Hugo Mercier is among the researchers now asserting that reason evolved to win arguments, not seek truth.

Mr. Mercier, a post-doctoral fellow at the University of Pennsylvania, contends that attempts to rid people of biases have failed because reasoning does exactly what it is supposed to do: help win an argument.

“People have been trying to reform something that works perfectly well,” he said, “as if they had decided that hands were made for walking and that everybody should be taught that.”

Think of the American judicial system, in which the prosecutors and defense lawyers each have a mission to construct the strongest possible argument. The belief is that this process will reveal the truth, just as the best idea will triumph in what John Stuart Mill called the “marketplace of ideas.”

Mr. Mercier and Mr. Sperber have skeptics as well as fans. Darcia Narvaez, an associate professor of psychology at the University of Notre Dame and a contributor to the journal debate, said this theory “fits into evolutionary psychology mainstream thinking at the moment, that everything we do is motivated by selfishness and manipulating others, which is, in my view, crazy.”

To Ms. Narvaez, “reasoning is something that develops from experience; it’s a subset of what we really know.” And much of what we know cannot be put into words, she explained, pointing out that language evolved relatively late in human development.

“The way we use our minds to navigate the social and general worlds involves a lot of things that are implicit, not explainable,” she said.

On the other side of the divide, Jonathan Haidt, a psychology professor at the University of Virginia, said of Mr. Sperber and Mr. Mercier, “Their work is important and points to some ways that the limits of reason can be overcome by putting people together in the right way, in particular to challenge people’s confirmation biases.”

This “powerful idea,” he added, could have important real-world implications.

As some journal contributors noted, the theory would seem to predict constant deadlock. But Mr. Sperber and Mr. Mercier contend that as people became better at producing and picking
apart arguments, their assessment skills evolved as well.

“At least in some cultural contexts, this results in a kind of arms race towards greater sophistication in the production and evaluation of arguments,” they write. “When people are
motivated to reason, they do a better job at accepting only sound arguments, which is quite generally to their advantage.”

Groups are more likely than individuals to come up with better results, they say, because they will be exposed to the best arguments.

Mr. Mercier is enthusiastic about the theory’s potential applications. He suggests, for example, that children may have an easier time learning abstract topics in mathematics or physics if they are put into a group and allowed to reason through a problem together.

He has also recently been at work applying the theory to politics. In a new paper, he and Hélène Landemore, an assistant professor of political science at Yale, propose that the arguing and assessment skills employed by groups make democratic debate the best form of government for evolutionary reasons, regardless of philosophical or moral rationales.

How, then, do the academics explain the endless stalemates in Congress? “It doesn’t seem to work in the U.S.,” Mr. Mercier conceded.

He and Ms. Landemore suggest that reasoned discussion works best in smaller, cooperative environments rather than in America’s high-decibel adversarial system, in which partisans seek to score political advantage rather than arrive at consensus.

Because “individual reasoning mechanisms work best when used to produce and evaluate arguments during a public deliberation,” Mr. Mercier and Ms. Landemore, as a practical matter, endorse the theory of deliberative democracy, an approach that arose in the 1980s, which envisions cooperative town-hall-style deliberations. Championed by the philosophers John Rawls and Jürgen Habermas, this sort of collaborative forum can overcome the tendency of groups to polarize at the extremes and deadlock, Ms. Landemore and Mr. Mercier said. Anyone who enjoys “spending endless hours debating ideas” should appreciate their views, Mr. Mercier and Mr. Sperber write, though, as even they note, “This, of course, is not anargument for (or against) the theory.”